Comments on: Singapore Math
http://ask.metafilter.com/256083/Singapore-Math/
Comments on Ask MetaFilter post Singapore MathMon, 27 Jan 2014 21:23:52 -0800Mon, 27 Jan 2014 21:35:40 -0800en-ushttp://blogs.law.harvard.edu/tech/rss60Question: Singapore Math
http://ask.metafilter.com/256083/Singapore-Math
I'm trying to help my 3rd grader with his math homework, but we are stuck on one problem. I can solve it using Algebra, but I'm trying to figure out how to explain it to him using the <a href="http://files.eric.ed.gov/fulltext/EJ848499.pdf">Singapore method</a> that he's taught in school. Note that he hasn't learned how to add negative numbers, which puts a crimp on the methodology. <br /><br /> Problem: In 2 years, Tom will be twice as old as he was 5 year ago. How old is Tom now?<br>
<br>
My solution: x+2=2(x-5). If you solve for x, the answer is 12<br>
<br>
The Singapore solution? This is where I am stuck. I don't understand how to use the bar ("strip diagram") method to model the problem in a way that a 3rd grader taught the Singapore method can solve.post:ask.metafilter.com,2014:site.256083Mon, 27 Jan 2014 21:23:52 -0800agogmathhomeworkresolvedBy: one_bean
http://ask.metafilter.com/256083/Singapore-Math#3721604
Draw a strip. Divide the strip in half (to represent the "twice as old" part). Split the right hand half about 2/3 along (okay, 5/7 along). You now have three strips. The right one is labeled 2, the middle one is labeled 5. The left strip is labeled equal to the right hand two. That's what he'll solve, and then can add that to the 5 to get the current age:<br>
<br>
<br>
|--------------|---------|----|<br>
\_____?____/\__5___/\_2_/<br>
<br>
? = 5 + 2comment:ask.metafilter.com,2014:site.256083-3721604Mon, 27 Jan 2014 21:35:40 -0800one_beanBy: SLC Mom
http://ask.metafilter.com/256083/Singapore-Math#3721605
[_____?_____][___5___][___2___]<br>
[____________________________]<br>
<br>
I think.comment:ask.metafilter.com,2014:site.256083-3721605Mon, 27 Jan 2014 21:38:51 -0800SLC MomBy: SLC Mom
http://ask.metafilter.com/256083/Singapore-Math#3721606
Or what one_bean said.comment:ask.metafilter.com,2014:site.256083-3721606Mon, 27 Jan 2014 21:39:22 -0800SLC MomBy: tinymegalo
http://ask.metafilter.com/256083/Singapore-Math#3721608
<a href="http://imgur.com/b891U9e">I agree</a> with the previous posts. I think to explain this most clearly, you should divide it into two problems.<br>
<br>
1) What is the future age? 2+5+(2+5)=14<br>
2) What is the current age? 14-2=12comment:ask.metafilter.com,2014:site.256083-3721608Mon, 27 Jan 2014 21:41:29 -0800tinymegaloBy: viggorlijah
http://ask.metafilter.com/256083/Singapore-Math#3721643
Parent in Singapore. No algebra until grade 6 or 7 here. I think it would go like this:<br>
<br>
|-----------------|------5------|--2--|<br>
\_____1/2_____/\_____1/2______/<br>
<br>
Where you would draw curly brackets underneath to show that each box is 1/2 and 1/2 (split into 5/2) fractionwise (equal parts) and then you could say that:<br>
<br>
Tom in two years is: (5+2) / 1/2 = 7*2 = 14<br>
Tom is now: 14-2 = 12comment:ask.metafilter.com,2014:site.256083-3721643Mon, 27 Jan 2014 23:05:43 -0800viggorlijahBy: disconnect
http://ask.metafilter.com/256083/Singapore-Math#3721781
I'd draw it like this. Start with a bar marked to indicate "present" (using an I below):<br>
<br>
I<br>
<br>
Add two dashes ("In two years...")<br>
<br>
I--|<br>
_2_<br>
<br>
Here's where it gets kind of tricky. I had to jump ahead to the end ("... as he was 5 years ago."):<br>
<br>
|-----I--|<br>
__5___2_<br>
<br>
Then go back to the middle of the sentence and add the last segment, noting that time increases to the right:<br>
<br>
|-------|-----I--|<br>
\__?__/\_5_|_2_/<br>
<br>
Neat method!comment:ask.metafilter.com,2014:site.256083-3721781Tue, 28 Jan 2014 07:39:49 -0800disconnectBy: agog
http://ask.metafilter.com/256083/Singapore-Math#3723311
Thanks, everyone! Every answer on here looks correct. I marked a couple as the best answer because they explained a couple of extra steps that are important from a 3rd graders perspective, but I was really impressed with all of the responses.<br>
<br>
Thanks for the help!comment:ask.metafilter.com,2014:site.256083-3723311Wed, 29 Jan 2014 21:48:49 -0800agog